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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - Scene Graph - Block Guy</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<div class="description">
A human hierarchy using a scene graph
</div>
<canvas id="canvas"></canvas>
</body>
<!-- vertex shader -->
<script id="vertex-shader-3d" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute vec4 a_color;

uniform mat4 u_matrix;

varying vec4 v_color;

void main() {
  // Multiply the position by the matrix.
  gl_Position = u_matrix * a_position;

  // Pass the color to the fragment shader.
  v_color = a_color;
}
</script>
<!-- fragment shader -->
<script id="fragment-shader-3d" type="x-shader/x-fragment">
precision mediump float;

// Passed in from the vertex shader.
varying vec4 v_color;

uniform vec4 u_colorMult;
uniform vec4 u_colorOffset;

void main() {
   gl_FragColor = v_color * u_colorMult + u_colorOffset;
}
</script>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="resources/webgl-utils.js"></script>
<script src="resources/m4.js"></script>
<script src="resources/primitives.js"></script>
<script>
"use strict";

   var TRS = function() {
     this.translation = [0, 0, 0];
     this.rotation = [0, 0, 0];
     this.scale = [1, 1, 1];
   };

   TRS.prototype.getMatrix = function(dst) {
     dst = dst || new Float32Array(16);
     var t = this.translation;
     var r = this.rotation;
     var s = this.scale;
     m4.translation(t[0], t[1], t[2], dst);
     m4.xRotate(dst, r[0], dst);
     m4.yRotate(dst, r[1], dst);
     m4.zRotate(dst, r[2], dst);
     m4.scale(dst, s[0], s[1], s[2], dst);
     return dst;
   };

   var Node = function(source) {
     this.children = [];
     this.localMatrix = m4.identity();
     this.worldMatrix = m4.identity();
     this.source = source;
   };

   Node.prototype.setParent = function(parent) {
     // remove us from our parent
     if (this.parent) {
       var ndx = this.parent.children.indexOf(this);
       if (ndx >= 0) {
         this.parent.children.splice(ndx, 1);
       }
     }

     // Add us to our new parent
     if (parent) {
       parent.children.push(this);
     }
     this.parent = parent;
   };

   Node.prototype.updateWorldMatrix = function(parentWorldMatrix) {

     var source = this.source;
     if (source) {
       source.getMatrix(this.localMatrix);
     }

     if (parentWorldMatrix) {
       // a matrix was passed in so do the math
       m4.multiply(parentWorldMatrix, this.localMatrix, this.worldMatrix);
     } else {
       // no matrix was passed in so just copy local to world
       m4.copy(this.localMatrix, this.worldMatrix);
     }

     // now process all the children
     var worldMatrix = this.worldMatrix;
     this.children.forEach(function(child) {
       child.updateWorldMatrix(worldMatrix);
     });
   };



function main() {
  // Get A WebGL context
  /** @type {HTMLCanvasElement} */
  var canvas = document.querySelector("#canvas");
  var gl = canvas.getContext("webgl");
  if (!gl) {
    return;
  }

  // creates buffers with position, normal, texcoord, and vertex color
  // data for primitives by calling gl.createBuffer, gl.bindBuffer,
  // and gl.bufferData
  const cubeBufferInfo   = primitives.createCubeWithVertexColorsBufferInfo(gl, 1);

  // setup GLSL program
  var programInfo = webglUtils.createProgramInfo(gl, ["vertex-shader-3d", "fragment-shader-3d"]);

  function degToRad(d) {
    return d * Math.PI / 180;
  }

  function rand(min, max) {
    return Math.random() * (max - min) + min;
  }

  function emod(x, n) {
    return x >= 0 ? (x % n) : ((n - (-x % n)) % n);
  }


  var cameraAngleRadians = degToRad(0);
  var fieldOfViewRadians = degToRad(60);
  var cameraHeight = 50;

  var objectsToDraw = [];
  var objects = [];
  var nodeInfosByName = {};

  // Let's make all the nodes
  var blockGuyNodeDescriptions =
    {
      name: "point between feet",
      draw: false,
      children: [
        {
           name: "waist",
           translation: [0, 3, 0],
           children: [
             {
               name: "torso",
               translation: [0, 2, 0],
               children: [
                 {
                   name: "neck",
                   translation: [0, 1, 0],
                   children: [
                     {
                       name: "head",
                       translation: [0, 1, 0],
                     },
                   ],
                 },
                 {
                   name: "left-arm",
                   translation: [-1, 0, 0],
                   children: [
                     {
                       name: "left-forearm",
                       translation: [-1, 0, 0],
                       children: [
                         {
                           name: "left-hand",
                           translation: [-1, 0, 0],
                         },
                       ],
                     },
                   ],
                 },
                 {
                   name: "right-arm",
                   translation: [1, 0, 0],
                   children: [
                     {
                       name: "right-forearm",
                       translation: [1, 0, 0],
                       children: [
                         {
                           name: "right-hand",
                           translation: [1, 0, 0],
                         },
                       ],
                     },
                   ],
                 },
               ],
             },
             {
               name: "left-leg",
               translation: [-1, -1, 0],
               children: [
                 {
                   name: "left-calf",
                   translation: [0, -1, 0],
                   children: [
                     {
                       name: "left-foot",
                       translation: [0, -1, 0],
                     },
                   ],
                 }
               ],
             },
             {
               name: "right-leg",
               translation: [1, -1, 0],
               children: [
                 {
                   name: "right-calf",
                   translation: [0, -1, 0],
                   children: [
                     {
                       name: "right-foot",
                       translation: [0, -1, 0],
                     },
                   ],
                 }
               ],
             },
           ],
        },
      ],
    };

  function makeNode(nodeDescription) {
    var trs  = new TRS();
    var node = new Node(trs);
    nodeInfosByName[nodeDescription.name] = {
      trs: trs,
      node: node,
    };
    trs.translation = nodeDescription.translation || trs.translation;
    if (nodeDescription.draw !== false) {
      node.drawInfo = {
        uniforms: {
          u_colorOffset: [0, 0, 0.6, 0],
          u_colorMult: [0.4, 0.4, 0.4, 1],
        },
        programInfo: programInfo,
        bufferInfo: cubeBufferInfo,
      };
      objectsToDraw.push(node.drawInfo);
      objects.push(node);
    }
    makeNodes(nodeDescription.children).forEach(function(child) {
      child.setParent(node);
    });
    return node;
  }

  function makeNodes(nodeDescriptions) {
    return nodeDescriptions ? nodeDescriptions.map(makeNode) : [];
  }

  var scene = makeNode(blockGuyNodeDescriptions);

  requestAnimationFrame(drawScene);

  // Draw the scene.
  function drawScene(time) {
    time *= 0.001;

    webglUtils.resizeCanvasToDisplaySize(gl.canvas);

    // Tell WebGL how to convert from clip space to pixels
    gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

    gl.enable(gl.CULL_FACE);
    gl.enable(gl.DEPTH_TEST);

    // Clear the canvas AND the depth buffer.
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

    // Compute the projection matrix
    var aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
    var projectionMatrix =
        m4.perspective(fieldOfViewRadians, aspect, 1, 2000);

    // Compute the camera's matrix using look at.
    var cameraPosition = [4, 3.5, 10];
    var target = [0, 3.5, 0];
    var up = [0, 1, 0];
    var cameraMatrix = m4.lookAt(cameraPosition, target, up);

    // Make a view matrix from the camera matrix.
    var viewMatrix = m4.inverse(cameraMatrix);

    var viewProjectionMatrix = m4.multiply(projectionMatrix, viewMatrix);

    // Draw objects

    // Update all world matrices in the scene graph
    scene.updateWorldMatrix();

    var adjust;
    var speed = 3;
    var c = time * speed;
    adjust = Math.abs(Math.sin(c));
    nodeInfosByName["point between feet"].trs.translation[1] = adjust;
    adjust = Math.sin(c);
    nodeInfosByName["left-leg" ].trs.rotation[0] =  adjust;
    nodeInfosByName["right-leg"].trs.rotation[0] = -adjust;
    adjust = Math.sin(c + 0.1) * 0.4;
    nodeInfosByName["left-calf" ].trs.rotation[0] = -adjust;
    nodeInfosByName["right-calf"].trs.rotation[0] =  adjust;
    adjust = Math.sin(c + 0.1) * 0.4;
    nodeInfosByName["left-foot" ].trs.rotation[0] = -adjust;
    nodeInfosByName["right-foot"].trs.rotation[0] =  adjust;

    adjust = Math.sin(c) * 0.4;
    nodeInfosByName["left-arm" ].trs.rotation[2] =  adjust;
    nodeInfosByName["right-arm"].trs.rotation[2] =  adjust;
    adjust = Math.sin(c + 0.1) * 0.4;
    nodeInfosByName["left-forearm" ].trs.rotation[2] =  adjust;
    nodeInfosByName["right-forearm"].trs.rotation[2] =  adjust;
    adjust = Math.sin(c - 0.1) * 0.4;
    nodeInfosByName["left-hand" ].trs.rotation[2] =  adjust;
    nodeInfosByName["right-hand"].trs.rotation[2] =  adjust;

    adjust = Math.sin(c) * 0.4;
    nodeInfosByName["waist"].trs.rotation[1] =  adjust;
    adjust = Math.sin(c) * 0.4;
    nodeInfosByName["torso"].trs.rotation[1] =  adjust;
    adjust = Math.sin(c + 0.25) * 0.4;
    nodeInfosByName["neck"].trs.rotation[1] =  adjust;
    adjust = Math.sin(c + 0.5) * 0.4;
    nodeInfosByName["head"].trs.rotation[1] =  adjust;
    adjust = Math.cos(c * 2) * 0.4;
    nodeInfosByName["head"].trs.rotation[0] =  adjust;

    // Compute all the matrices for rendering
    objects.forEach(function(object) {
      object.drawInfo.uniforms.u_matrix = m4.multiply(viewProjectionMatrix, object.worldMatrix);
    });

    // ------ Draw the objects --------

    var lastUsedProgramInfo = null;
    var lastUsedBufferInfo = null;

    objectsToDraw.forEach(function(object) {
      var programInfo = object.programInfo;
      var bufferInfo = object.bufferInfo;
      var bindBuffers = false;

      if (programInfo !== lastUsedProgramInfo) {
        lastUsedProgramInfo = programInfo;
        gl.useProgram(programInfo.program);

        // We have to rebind buffers when changing programs because we
        // only bind buffers the program uses. So if 2 programs use the same
        // bufferInfo but the 1st one uses only positions the when the
        // we switch to the 2nd one some of the attributes will not be on.
        bindBuffers = true;
      }

      // Setup all the needed attributes.
      if (bindBuffers || bufferInfo !== lastUsedBufferInfo) {
        lastUsedBufferInfo = bufferInfo;
        webglUtils.setBuffersAndAttributes(gl, programInfo, bufferInfo);
      }

      // Set the uniforms.
      webglUtils.setUniforms(programInfo, object.uniforms);

      // Draw
      gl.drawArrays(gl.TRIANGLES, 0, bufferInfo.numElements);
    });

    requestAnimationFrame(drawScene);
  }
}

main();
</script>
</html>


